Nowadays, the average door operator is set up to open or close the rolling door at a constant speed. That is, a rolling door is operated at a constant speed. However, in cases where the opening or closing stroke of the rolling door is relatively long, the waiting time will be lenghty, and both time and energy would be wasted. Therefore, a rolling door system with a variable operation speed is urgently needed by the industries and the public. There are existing art that make use of absolute positions to control the rolling speed of a rolling door, in which the rolling speed is accelerated or decelerated as a predetermined position is reached. However, such control mode is not flexible enough to cope with different requirements and changes, and is only applicable to a rolling door that is to be fully opened or closed.
In general, specifications of door operators are fixed, but specifications of door panels may be different to cope with different requirements, and on-site conditions for installing the rolling doors. Therefore, the size, type or material of the door panel may be different, which will result in weight difference. However, door panels of different weights will have different operation loads. If the rolling speed of the rolling door is controlled by only the absolute position, the door operator may be damaged due to overload during acceleration, or may result in risk as the operation speed of the door operator may be too fast due to underweight of the load.
With the recent improvement in the technology of detecting the real-time position of the rolling door, it is now possible to provide a rolling door system with variable operation speed. With reference to U.S. patent publication No. 2016/0090772 A1 entitled “Door Operator System Capable of Detecting a Current-Time Position of a Movable Barrier/Door Operator System Having a Device for Detecting Real-time Position of a Rolling Door”, a first angular position sensing unit is used to measure a rotational angle of an output shaft of a motor or a door shaft of a rolling door directly or indirectly, and a revolution counting unit is used to count the number of revolutions for the output shaft of the motor or the door shaft of the rolling door, to thereby calculate a real-time (current-time) absolute position of the rolling door.
However, even though it is possible to calculate the real-time absolute position of the rolling door, there are still difficulties in the application of the concept to control the operation speed of the rolling door system. The present invention overcomes all the problems and successfully implements a rolling door system with variable operation speed.